Don't return immediately from reboot commands.

The reboot commands return too fast, interfering with testing.
Add a pause(), which will allow the device time to complete the
reboot.

Change-Id: Ie9cc6eea67b7ff662ec71ea2329cbb94f8d55404
Bug: 11369303
utils: Add ProcessCallStack to collect stack traces for all threads in a process

- Also add a Printer class (print lines to logcat, fd, or strings)

Bug: 11324229
Change-Id: I78435ed49aa196a0efb45bf9b2d58b62c41737d3

Conflicts:
	libutils/Printer.cpp
	libutils/ProcessCallStack.cpp
utils: Fix broken build

Bug: 11324229
Change-Id: I7e4f514c5531e4c0c11bb0ba5d67e4dabbcd5792

Conflicts:
	libutils/ProcessCallStack.cpp
utils: Fix broken sdk build on windows

Bug: 11324229
Change-Id: Ia50e79b5e2430faea77b0c98902e8e018fb9ceff

Conflicts:
	libutils/Printer.cpp